Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for a blower motor that does not operate regardless of the desired blower motor speed.
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This step tests for a blower motor that operates, yet does not accurately respond to the desired blower motor speed.
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This step verifies that there is power to the HVAC control assembly.
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The voltage will vary between 0-5 volts during normal operation. The HVAC control assembly connector must be connected during this step.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: Air does not flow correctly from the air distribution outlets. | ||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||
2 |
Is the blower motor OFF? | -- | Go to Step 3 | Go to Blower Motor Always On | ||||||||
Place the blower motor control in each speed position. Does the blower motor operate at all? | -- | Go to Step 4 | Go to Blower Motor Inoperative | |||||||||
Does the blower motor operate correctly for each speed position? | -- | Go to Step 5 | Go to Blower Motor Malfunction | |||||||||
Is the HVAC control assembly inoperative in all positions? | -- | Go to Step 6 | Go to Step 16 | |||||||||
6 |
Does the mode actuator drive shaft rotate for each selected position? | -- | Go to Step 7 | Go to Step 8 | ||||||||
7 | Inspect the mode door and the mode actuator for the following conditions:
Did you find and correct the condition? | -- | Go to Step 23 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||||
8 | Test the ignition 1 voltage circuit of the mode actuator for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 9 | ||||||||
9 | Test the ground circuit of the mode actuator for an open or high resistance. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 10 | ||||||||
10 | Test the 5-volt reference circuit of the mode actuator for the following:
Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 11 | ||||||||
11 | Test the signal circuit of the mode door actuator for the following:
Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 12 | ||||||||
12 | Test the mode door control circuit of the mode actuator for the following:
Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 13 | ||||||||
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Important: Connect the mode actuator connector and the HVAC controller connector in order to correctly perform the test.
Does the mode actuator drive shaft rotate and does the voltage change? | -- | Go to Step 14 | Go to Step 18 | |||||||||
14 |
Is the voltage measurement near the specified values for each setting? | 0 V toward DEF 5 V toward FLR 2.5 V stationary | Go to Step 15 | Go to Step 20 | ||||||||
15 | Inspect the mode door for a mechanical condition or for a condition that allows excessive travel to the door. Did you find and correct the condition? | -- | Go to Step 23 | -- | ||||||||
16 | Test the ignition 1 voltage circuit of the HVAC controller for an open, for a high resistance or for a short to ground. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 17 | ||||||||
17 | Test the ground circuit of the HVAC controller for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 20 | ||||||||
18 | Inspect for bad connections at the harness connector of the mode actuator. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 19 | ||||||||
19 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 | ||||||||
20 | Inspect for bad connections at the harness connector of the HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 22 | ||||||||
21 | Replace the mode actuator. Refer to Mode Control Cam Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||
22 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||
23 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 | ||||||||
